Single station variable length stroke motor control system



J. ROBINSON E 2,918,902

Dec. 29, I959 SINGLE STATION VARIABLE LENGTH STROKE MOTOR CONTROL SYSTEM 2 Sheets-Sheet 1 Filed Dec. 6, 1954 SN MOM TS N mmo R VBC m T Rm A EN wk 2O 22 y Fl G.|

Dec. 29, 1959 J. ROBINSON ETAL SINGLE STATION VARIABLE LENGTH STROKE MOTOR cormox. SYSTEM Filed Dec. 6, 1954 2 Sheets-Sheet 2 -mounted in the double acting cylinder.

is 2,918,902 Patented Dec. 29, 1959 SINGLE srAnoN VARIABLE LENGTH STROKE MOTOR CONTROL SYSTEM James Robinson, Huntington Woods, and Kenneth Court,

Detroit, Mich., assignors to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Application December 6, 1954, Serial No. 473,418

13 Claims. (Cl. 121-38) This invention relates to power transmissions, and is particularly applicable to those of the type comprising two or more fluid pressure energy translating devices, one of which may function as a pump and another as a fluid motor.

The invention particularly pertains to hydraulic transmission systems of the type incorporating a double acting cylinder for actuating a load device wherein the length of stroke of the main piston may be remotely adjusted and controlled. Systems of this type have been particularly useful for operating the trailing agricultural implement of a towing tractor, such as a plow. The operator of such a system may from the tractor seat not only control the directional operation of the main piston of the cylinder for raising and loweringthe implement but may also adjust from the tractor seat a device or member for limiting the stroke of the main piston.

One such form of stroke adjusting device is an auxiliary hydraulically actuated stop piston which may be fioatably Although a separate source of pressure fluid may be utilized to operate the auxiliary piston it may be operated together with the main'piston of the cylinder from a single source of pressure fluid such as a fluid pump driven from the power take-01f of the tractor.

It has been the practice to utilize in such systems one :manually operated directional control valve for controlpack it is necessary for the operator of the system to focus his attention on and to manipulate either one two directionalcontrol valve handles.

It is therefore an object of this invention to provide an improved hydraulic transmission system for remotely controlling the directional operation and stroke adjustment of a double acting hydraulic cylinder or motor for driving a load device.

It is another object of this invention to provide a hydraulic system incorporating a fluid cylinder or motor for driving a load device in which both the directional operation'of the motor and the stroke length of the main piston is controlled and adjusted by a single directional control valve having one manually operated control handle for both directional and stroke adjustment operations of the motor.

actuation ofjthe motor in theconventional manner for nrivingthe load device. l

It is still another object of this invention to provide a hydraulic power transmission of the type and for the purposes recited wherein anactuator and strokelimiting member for the actuator mounted at. one station may bothbe controlled and operated from a remote station at which is located a pressure fluid source and single manually operated control, with the two stations interconnected by only two, dual function, supply and return conduits;

It is a further object of this invention to provide a directional control valve of novel construction which is sensitive to flow conditions to port fluid .to desired locations or elements of a hydraulic system, such as to the main'piston or to an auxiliary stroke limiting piston of a double acting cylinder. I

It is still another object of this invention to provide a hydraulic power transmission system of the type and for the purposes recited which is relatively simpler and more economical and eflicient in construction and operation, which reduces the number of manually operated controls and plumbing lines, and which is more convenient and simpler for the operator of the system.

Figure 1 is a diagrammatic view of a hydraulic power transmission system embodying a preferred formof the present invention.

FigureZ is a sectional view of the directional control valve incorporated in the'power transmission system illustrated' in Figure 1.

Referring to Figure llthere is shown a hydraulic power transmission system adapted for actuating" and remotely controllin g the operation of a load device, for example, a trailingagricultural'implement of a tractor, such as a plow. The hydraulic system includes'a pressure fluid source comprising a fluid pump 10 supplied with fluid from a tank 12, a fluid motor 14 for driving the load device, not shown, and interconnected with the pressure fluid source and the motor a combined directional and flow'control valve 16 and a flow sensitive directional control valve 18. The pump lO is adaptedto be driven by a p'rimeImover, not shown, suchas' the power. takeoff of a tractor. k I

The pressure fluid source and directional control valve are mounted at one station which is indicated in block form and by the numeral 19, such as the tractor, while the motor including a hydraulically adjustable stop member, and a flow sensitive valve are mounted at a remote station which is also indicated in block form by the nu meral 21, such as the trailing implement of 'a tractor. The arrangement is such that only two conduits are necessary for interconnecting the stations and for controlling at one station both the motor and motorvstop member remotely located at the other station. I

The inlet 20 of the pump 10 is connected to the tank 12, by a supply conduit 22 whilethe outlet, 24 thereof type comprising a cylinder 34 having shiftably mounted. therein' affluid operated main piston 36 and an auxiliary I piston38 the latter 'ofwhich may behydra'ulically adjusted and locked to limit the stroke of the main piston in one direction. A'piston rod 40 associated with the main piston '36 extends from one end of the cylinder for connection to a load device. A tubular member 42, which is hollow to provide a passage 44 extending completely there through to form openings at opposite ends indicated by the "numerals 4'6 and 48, is mounted atone end in; a closure member 50 of the cylinder and extends into a hollow section 52 of the main piston and rod. The auxiliary piston 33 is floatably mounted on the tubular member 42. The circumference of the tubular member 42 in relation to the area of the hollow section 52 of the main piston and rod is adapted to provide a passage within the rod and main piston around the periphery of the tubular member which is indicated by the numeral 54.

Three expansible chambers are formed within the cylinder one of which is located between the inner face of the cylinder closure member 50 and the auxiliary piston 38 which is indicated by the numeral 56. Another chamber, indicated by the numeral 58, is formed between the opposite face of the auxiliary piston 38 and the adjacent face of the main piston 36. The remaining expansible chamber 60 is formed between the opposite face of the main piston 36 and the inner face of a closure member 62 at the rod end of the cylinder. The cylinder 34 is provided with a motor port 64 at the rod end of the cylinder which leads to the main piston chamber 60 and a motor port 66 is located in the opposite end of the cylinder leading to the chamber 56. The chamber 58 is connected to the opening 46 of the tubular member 42 by means of the passage 54 surrounding the outer periphery of the tubular member 42 within the hollow section 52 of the piston 36 and rod 40, and the opening 48 and the passage 44 of the tubular member 42.

The present invention utilizes one manually operated directional control valve 16 to control the operation of both pistons with the cooperation of the automatically operated flow sensitive directional control valve 18. Valve 16 may be of the well known type disclosed in the patent to Kirkham, No. 2,448,532 or of the type disclosed in the patent to Stephens, No. 2,448,557, which type of valve is shown schematically in Figure 1 and is shown in detail in Figure 2. The valve will be described first as shown schematically in Figure 1 and will subsequently be described in more detail as disclosed in Figure 2. The control valve 16 is in essence a four-way directional valve which in addition to the pressure port 28 is provided with a tank return port 68 and two motor ports 69 and 70. The control valve 16 is provided with a valve spool, the construction of which is shown in Figure 2, for controlling intercommunication between the ports Which is manually operable by a control handle indicated by the numeral 71. In the neutral position of the handle shown, indicated by the letter N, the pressure port 28 is connected to the tank port 68 for unloading the pump while the motor ports 69 and 70 are blocked from communication with each other and the pressure and tank ports. In the position of the lever arm indicated by R1 and R-2 the pressure port 28 is connected to the motor port 70 whi'e the motor port 69 is connected to the tank port 68. In the position of the lever arm indicated by Ll and -L-Z the pressure port 28 is is connected to the motor port 69 and the motor port 79 is connected to the tank port 68.

The directional control valve 16 is of the type which when the lever arm is in either of the positions R-l or L-l will only be partially open so as to restrict the flow of fluid therethrough and thereby direct less than full pump displacement to the motor or to the fiow sensitive valve 18. Fluid from the pump in excess of the restricted quantity will be exhausted to tank 12 through the relief valve 30. When the control handle 71 is shifted to either of the positions R-Z or L-Z the directional valve will be in the wide open position to direct full pump displacement to the motor 14 or to the flow sensitive valve 18.

The motor port 69 of control valve 16 is connected to the cylinder motor port 64 by a conduit 72 and the remaining motor port 70 of the control valve 16 is connected to an external connection port 74 of the fiow sensitive valve 18 by a conduit 76. The port 74 functions in one direction of motor operation as a pressure delivery inlet port and in the opposite direction of motor operation as a motor return port. The conduits 72 and 76 may have incorporated therein flexible hoses, as shown, when for example the transmission is utilized to operate a trailing implement of a tractor. The tank port 68 is connected to the tank 12 by a return conduit 77 leading to the conduit 32.

The directional control valve 16 incorporates a spool or piston for controlling intercommunication between the ports which remains in the position operated to until displacement from the motor ceases. In control valves of this type a restriction or valve of the back pressure type may be placed in the valve body passages which return fluid from the motor to build up a pressure on either one of two pressure responsive end surfaces of the valve spool sufficient to overcome the resistance of a centering spring which returns the valve spool to a neutral position when motor displacement ceases.

For the purposes of convenience the pressure responsive end surfaces of the valve spool indicated by the numerals 79 and 81 and the valve circuit for the surfaces have been shown in Figure 1 externally of the valve body. A valve passage 83 which is adapted to connect the conduit 72 to the conduit 77 when the valve spool is shifted rightwardly is connected to the endsurface 79 by a passage 85. A restriction 87 is placed in the passage 83 to create a pressure on the end surface 79 when motor displacement is conducted from the conduit 72 to 77 sufiicient to maintain the valve spool in the rightward operating position. A passage 89 adapted to connect the motor conduit 76 to the tank conduit 77 when the valve spool is shifted leftwardly is connected to the other end surface 81 of the valve spool by a passage 91. A restriction 93 is placed in the passage 89 and creates a pressure on the end surface 81 when motor displacement is conducted from the motor conduit 76 to the tank conduit 77 suflicient to maintain the valve spool in the leftward operating position. When motor displacement ceases the pressure in either of the lines or 91 decreases to permit the valve spool to be automatically operated by the centering spring to the neutral position.

Referring now to Figure 2, valve 16 is composed of a body 152 having a longitudinal bore 154 extending completely therethrough which is closed at opposite ends thereof. Suitably mounted within the longitudinal bore 154 is a valve spool indicated by the numeral 156 which has a portion 158 extending from the bore outside the body and which may have a lever thereon 71 as indicated in Figure 1.

The body 152 i provided with a pressure port. 28 which opens to a pressure chamber 168 connected by branches 162 and 164 to the longitudinal bore 154. The external tank connection port 68 leads to the return passage 77 (shown exteriorly of the valve shown in Figure l). The return passage 77 is directly connected to a centrally located valve bore tank port 166.

The spool 156 has a center land 168 which in the position of the valve spool shown in Figure 2 connects the pressure chamber 160 and its branches 162 and 164 to the tank port 166 so as to form a direct pump unloading connection in the neutral position of the valve shown from the pump 10 to the tank 12. The valve spool 156 is biased to the unloading position shown by a centering spring 170.

When the valve spool is shifted to the left or right, it engages respectively with bore sealing portions 172 or 174, and lands 176 and 178 to the left and right respectively of center land 168 cooperate with the center land 168 to disconnect the branches 162 or 164 from the enlarged tank port 166. When shifted to the left, a transverse valve spool port 180 cracks over a valve bore motor port 182. The pressure branch 162 is then connected by a valve spool transverse port 184 to a hollow section 186 of the valve spool.

A check valve 188. biased to the position shown by a spring 190 is mounted in the hollow section 186, which check valveis opened by pump, now, which isthen free to new from the valve spool port}180 tothe valve bore motor port-182 and thence to -the external connection motor port 69 When the valve; spool 156;is shifted .rightwardly, the center land- 168 incooperation with its immediately adjoining land 178 cuts off the valve bore tank port 166 from the pressure port by crossing over into the sealing area 174, and-the pressure branch 164 is connected by means of a valve spooltransverse port l92 'to a hollow section 194 in the right end-of the valve spool.

A check valve 196 is mounted inthe hollow section 194 and is biased to the position-shown by a spring 198. Pressure fluid from the pressure branch 164 enters the hollow section 194 by means-of'the transverse port 192, shifts the check valve 196 n'ghtwardly' and pressure fluid .is conducted by means of a valve spool transverse port .200 in the valve spool to a valve bore motor port 202 which is directly connected to the external connection ;motor port 70, shown in Figure 1.- I v The valve spool 156 may be shifted partially right- 'wardly to a-position where the valve spool transverse port L200 cracks slightly over the valve bore motor port 202 so-as to meter flow to the flow sensitive valve 18 The valve spool 156-may also be shifted further iightwardly 'so as to completely open the transverse port 200 to valve *motor-port 202and thus direct a large fiow to the flow :sensitive valve 18. Likewise the valve spool 156 may lbe shifted partially leftwardly to the L 1 position whereby the valve spool transverse port 180 is opened slightly to the valve bore motor port 182; Pump flow tmay thus be metered in said position to the motor cylintder-14. When the valve spool 156 is shifted completely to tthe left, the valve spool transverse port 180 is open com- ;pletely' to the valve bore motor port 182 and full pump iflow isconducted to the motor cylinder 14;:-

Valve spool 156 is provided with'end sections of reduced diameter which provides a left end, pressure effective annular area 79 and a duplicate right end pressure effective area 81, which are shown schematically in Figure l. When-valve spool 156 isshifted leftwardly, fluid returning to the motor port 202 isconnected by the right end reduced portion of the. valve spool to a valve tank return port 204. From the tankreturn port 204, returnflow is conducted 'by a passage 91 through an- :striction 93 to a passage 89 and thence by means of valve boretank port 166 and passage 77 conducted to theexternal tank connection port 68. The restriction-'93 causes a pressure build-up which acts -on the annular spool area 81 and which is suflicient to overcome the spring 1.70 in order to maintain the valve spool 156 shifted to the'leftward operating position. When'return flow ceases there no longer is a pressure build-up ahead of the restriction 93 andthe spring-170 returns the valve spool 156 to the neutral position.

When valve spool 156 is shifted-rightwardly,-fiuid returning to motor port 182 is connected by the leftend reduced portion of the valve spoolto a duplicate tank return port 206. From the tank return port 206, return how is conducted by a passage85 through a restriction 87 to a passage 83 and thence by means of valve bore tank port 166 and passage 77 to the external tank connection port 68. The restriction 87 causes a-pressure lauild up which acts on the left end annular area 79 and is sufiicient to overcome the spring l70 to cause the valve :spool156 to remain shifted to the rightward operating position. When-return flow ceases there no longer is a pressure build-up ahead oftherestriction 87 and-the :spring 170 returns the valvespool-156 to' the neutral position.

The flow sensitive valve 18 comprises a'body'78 which .finaddition'to' the connection port 74 is provided with :a motor port 80 connected to the-cylinder port 66 and :to chamber 56 of motor '14 by a conduit- 82 and has a mo ten port 84' connected to the/tubular, opening port 46 and; to chamber 58 of motor 14 byga conduit 86; The body 78 has a centrally located longitudinal bore 88 closed at one end by an end cover 90 and the opposite open end of which comprises the double-function motor inlet and return port 74. The bore 88 is constructed with motor ports 92 ,and 94 7 located on opposite sides of an intermediate port The external connection motor ports 80 and 84 of the body are respectively connected to the valve'bore motor ports 92 and 94 by passages 98 and 100;

Communication between the several ports is controlled by a flow sensitive pistonvalve merhber indicated generally by the numeral 102 which isshiftably mounted in the bore 88 and forming-chambers 103 and at opposite endsof the bore. When the pump 10 is-connected to the port 74 of valve'18 and the control handle 71 of valve -16 is in the position R-l to restrict flow, the flow sensitive piston valve member 102 remains in the position shown to connect the inlet port 74 to the motor port 80. When the handle 71 of the control valve 16 is in the R2- position to permit high flow to the inlet port 74 the valve member 102 is shifted leftwardly to block port 74 from motor port 80 and to connect port 74 to motor port 84.

When the desired plowing depth' hasbeen reached the main piston 36 of the cylinder 34 will be in abutment with the auxiliary stop piston 38. If it is desired to plow at a slightly greater depth the control handle 71 of valve 16 may be shifted to the L-l position to connect the pump to the left end of motor14. The valve member 16 restricts flow to the motor in the Is-1" position and valve member-102 will remain in the position shown to conduct motor displacement from port 80 to the port 74 of valve 18. Wheneverthecontrol lever is shifted to the L-2 position the valve m'e'mber 102 is operated rightwardly because of the high flow conditions created to connect port84 to p'ort74 while closing motor port 80 to the port 74.

The valve member 102 has a longitudinal passage 104 extending completely therethrough opening at opposite ends to the chambers 103 and 105 which in the position of the valveshown is connected to the intermediate port 96 of the bore 88 by means of spaced apart transverse ports 106 and 108 opening to the port 96 and connected to the motor port 92 of the bore 88 by a transverse port 110. A restriction to large flow from or to the port 74, indicated by the numeral 112, is located in the longitudinal passage 104 adjacent the transverse port108. A venting check valve assembly-is mounted in the passage 104 comprising a poppet 114 biased by a spring 116 on a seat 118 formed in the passage 104. A spring 120 having a resistance greater than the resistance of spring 116 and mounted between snap rings 122 and 124 respectively abutting shoulders 126 and 128 of the valve member 102 biases the valve member 102 to the neutral position shown. The valve member 102 is constructed with substantially balanced pressure responsive end areas indicated generally by the numerals 130and 132, which are respectively exposed to the pressures existent in the chanibers 103 and 105. r

In the centered position of the valve member 102 shown, low inlet flow to the port 74 is blocked'from communication with the port 94 and the passage 100 by a right and land 134 of the valvemember. A land 136 between the transverse ports 106 and 108 permits flow from'the passage 104 to the valve motor port 96 by the medium of the transverse port 108 and from the motor port 96 to the passage 104 through the medium of transverse port 106. Aland 138 located between land 134 and land 136 blocks the passage 100 from transverse port 108 and intermediate port 96. I

When high inlet How is conducted to the'bore 88 from the inlet port 74 a pressure increase ahead of the restriction 112 in the passage 104 creates a differential pressure on the? end areas 130"and 132 ofthe valve therewith under high flow conditions.

member 102 sufi'icient to overcome the resistance of the spring 120 for operating the valve member 102 leftwardly and land 134 opens communication between the inlet port 74, chamber 103 and the passage 100 leading to motor port 84.

When the valve member 102 is operated in the opposite direction under the influence of high flow directed to the bore motor port 92 from motor port 80 and sensed by the restriction 112, the transverse port 108 is no longer in communication with the intermediate port 96 but with passage 100 and motor port 94. Displacement from the chamber 58 of the motor 14 is conducted from the passage 100 to the port 74, now acting as a return port, by a branched passage 140 having a seat opening 142 leading to the chamber 103 which is controlled by a poppet valve 144 biased to the closed position upon the seat 142 by a spring 146. With the valve member 102 shifted rightwardly the spring 146 of the poppet valve 144, the resistance of which is greater than that of the spring 120, is adapted to build up a pressure at the left end of the valve member 102 in chamber 105 sufiicient to maintain the valve in the rightward operating position until the displacement from the motor ceases.

Pressure on the right end area 130 of valve 102 will be low as port 74 during this operation is connected to tank 12. With transverse port 108 connected to motor port 84 the pressure existent ahead of poppet valve 144 is transmitted by means of passage 100, transverse port 108 and longitudinal passage 104 to act against the venting valve 114 and tending to maintain the valve seated. A substantially equal pressure sufiicient to maintain the valve shifted rightwardly against the urging of spring 120 is transmitted from chamber 56 of motor 14 to the left end surface 132 of valve 102 by means of conduit 82, motor port 80, passage 98, transverse port 110 and longitudinal passage 104. This pressure is also transmitted by the passage 104 to the opposite side of vent valve 114 to equalize the pressures thereon and the spring 118 will maintain the valve seated.

Rightward movement of the valve member 102 is limited by a shoulder 147 located on one side of the transverse port 110 coming into abutment with the snap ring 122 while leftward movement of the valve member is limited by a shoulder 149 located on the opposite side of the transverse port 110 coming into abutment with the snap ring 124.

A restriction 151 forming a portion of longitudinal passage 104 is located between the transverse ports 106 and 108. When the main piston of the motor is operated in abutment with the auxiliary piston the restriction 151 prevents free venting of fluid from chamber 56 of the motor through the venting valve 114 and thus prevents continued movement of the auxiliary piston which shifts slightly when the main piston comes into abutment With continued displacement from the motor 14 the main valve 16 would not be operated to the neutral position and the main piston would continue to shift the auxiliary piston. The restriction 151 thus aids in insuring operation of the main directional control valve 16 to the neutral position when the main motor piston has reached the limit of its rightward stroke under high flow conditions as determined by the position of the auxiliary motor piston.

In operation with the pump running, and assuming for the purpose of describing the system that the motor 14 is for the purpose of raising and lowering a plow to desired plowing depths, if the control handle 71 of directional valve 16 is manually shifted to the R-2 position high flow from the pump 10 will be conducted to the inlet port 74 of flow sensitive valve 18. Fluid from the pump 10.is conducted to port 74 of valve 18 by conduit 26, across the directional valve 16 through the medium of ports 28 and 70 and thence by conduit 76. Before the valve member 102 is operated leftwardly a slight amount of pump displacement is directed to t an ber 56 of motor'14 and as the valve 102 shifts leftwardl y the fluid displaced from the left end of valve 102 is also conducted to the chamber 56. The auxiliary piston 38 is thus shifted slightly together with the main piston 36 before the main piston shifts alone. As will be subsequently explained, when the main piston is shifted rightwardly to lower the plow the auxiliary piston also shifts slightly so that the system is self-correcting in returning and maintaining the auxiliary piston to the adjusted position.

High flow conducted to the inlet port 74 and chambe 103 of the valve 18 must flow through restriction 112 and a pressure increase immediately takes place ahead of the restriction to create a pressure differential in the chambers 103 and on the end areas 130 and 132 of the valve member 102 suflicient to overcome the resistance of the spring and to operate the valve 102 leftwardly until the shoulder 149 comes into abutment with snap ring 124. Land 134 of valve member 102 which formerly blocked port 74 from communication with valve bore motor port 94 now permits communication between said ports and fluid is conducted by conduit 86 to the tubular opening 46 of motor 14 and by means of tubular passage 44 and of piston rod passage 54 to motor chamber 58.

With the valve member 102 shifted leftwardly chamber 56 of the motor is blocked from the intermediate valve port 96 as the transverse port 106 has passed out of communication with the port 96. The main motor piston 36 will be actuated speedily leftwardly to raise the plow until it comes to the limit of its leftward stroke at which time flow from the motor chamber 60 which had been conducted to tank 12 by conduit 72, across the ports 69 and 68 of valve 16 to the conduits 77 and 32 ceases. During motor operation pressure increase take place in the passage 83 ahead of the restriction 87 in the valve 16 which conducts fluid from the motor. The pressure increases are transmitted by passage 85 to the end operating surface 79 of the valve spool to maintain the valve in the R-2 position. When flow from the motor ceases the pressure decreases at the valve spool end surface 79 and the valve spool is automatically operated to the N or neutral motor stop position.

The valve member 102 remains in the position operated to until the valve handle 71 is shifted from the N position to the L2 position at which time port 74 of valve 18 is connected to tank 12 by the directional valve 16 and the trappedpressure in chamber 103 on the right end surface of the valve member 102 is released. High flow from the pump 10 is directed across the ports 28 and 69 of directional valve 16 to chamber 60 of motor 14 and the main piston 36 of the motor is actuated speedily rightwardly to lower the plow. The spring 120 of valve member 102 initiates movement of the valve member 102 to the centered position and with high flow directed to chamber 60 of the motor 14 against the main piston of the motor, the auxiliary piston 38 is shifted slightly to displaced fluid from the chamber 56 to the motor port 80 of valve 18 and thence by passage 98 and transverse port 110 of the valve member 102 to the longitudinal passage 104. Because of the high flow tending to pass through the main restriction "112 of the valve a pressure differential is created on the opposite ends 130 and 132 of the valve member 102 to operate the same rightwardly from the neutral position until the shoulder 147 of the valve member comes into abutment with the snap ring 122. The transverse port 108 of the valve member passes out of communication with intermediate valve bore port 96 and the land 136 blocks communication between the valve bore motor port 94 and the intermediate port 96. The motor port 80 of valve 18 is thus blocked from communication withport 74 and the" fluid in-chamber 56 in back of the auxiliary pistca 38 is trapped and locks the piston 38 in awe-ma msit q t im t he r-i h atdstroke q themain 123. 1 636- iF d m the p mp lflii .cgnd rtedt th ber 60 of the motor-14 to actuate the. pistonfifi rightwardly until the piston 36 comes into abutment with the auxiliary piston 38. Displacement from the chamber 58 of the motor is conducted by means of the piston rod passage 54, tubular opening 48 an'd the passage 44 to the tubular opening 46 whence by means of conduit 8 6 it is conducted to the motor port 84 of valve18.

From the port 84 motor displacement is conductedby .Yalve passages 100 and 140 to the poppet valve 144 which .is operated to open theseat .142 from whence fluid is conducted to the chamber 103 and port 74. As trans- .verse port 108 is connected to the passage 100a divided flowmay take place but the. restrition 112; together with the resistance of valve spring 146 maintains sufiicient valve. operating back pressure. displacement is conducted byv conduit 76 and across the ports 70 and 68 .of directional: valve. 16 to the conduits 77 From the port 74 -fl uid and 32 and thence to, tank 12. Fluid returning from motor 14 in;th e passage 89 of the valve 16 must pass throughthe restriction 93 causing a; pressure increase ahead of the restriction which is trans- ;mitted, by passage 91 to the right end operatingsurface 81 of the valve spool to maintain the directional. valve 16 in the L-2 position.

When the main piston 36 of the motor 14 comes intoabutment with the auxiliary pis- .ton 38 the piston 38 is shifted slightly andthe slight v amount of fluid displaced from the chamber 56 is extruded through the vent valve 114 of valve member 102. This flow is dampened bythe restriction 151 andwith vcessation of motor displacement the pressure decreases at the right end operating surface 81 of the main directional valve spool causing the .valve 16 to be automatically operated to the N orneutral motor stop position. As tank pressure had been existent, at the right. end op- .erating surface 130 of valve member 102 the spring 120 will return the valve member 102 to the centered position. Fluid displaced from valve chamber 105 as the valve 102 shifts leftwardly to the centered position is A conducted through the passage 104 and the vent valve 114, the spring resistance of which is less than the op- .erating force of the spring 120, to the right endchamber 103 of the valve.

If it is desired to plow at aslightlygreater depth the control handle 71 of the directional-valve 16;. may be shifted to the Irl position and a low volumeof fiuid '-will be conducted to the chamber 60 of the motor to actuate the main piston 36. which -.will shift the auxiliary piston. Fluid will be displacedfrom thernotor chamber 56 to the motor port 80 from whence it is -conducted =by. the passage 98 to the valve bore motor port- 92 and by transverse port 110,- passage 104, transverse port; 6,

rnotor port 96, transverse port 108.back to the passage 104 and through the restriction 112 to chamber 103.,and thence to port 74 from where it is conducted ,tothe tank 12. The restriction 112 does not ofiera resistance to low flow so that the flow sensitive valve member l02 rema ins in the centered position.- The. operator of the system, ,when the required plowing depth has been reached, will manually return the control valve handle 71. to the N motor stop position.

If it is desired to raise the plow slightly the control handle 70 maybe shifted to the R-l position. Low

flow is conducted to the port 74 of flow -sensitive-valve 18 from whence it is conducted by the chamber.103,

pa s sage 104 through the restriction 112,;a nd around;the motor-"port 96 to the passage 104-by;m eans of'the ,transverse ports 108 and 106, and thence by; the transverse port 110, passage 98, motor port 80 and conduit 82 to the chamber 56 ofmotor 14. The auxiliary, piston .38

ispperated to also shift the main piston 36 and displacem ent from the motor chamber 60is conducted .b yaconduit 7 2 to the jdirectional control valve 16 and thence tgtank 12. 'Thecontrol handle 71 may be shifted to the the latter port of which is now connected to the k.

Thus, when the auxiliary piston 38 has been adjusted to a selected position the plow may be raised rapidly'by shifting the control-handle 71 of valve 16 to the R-2 position. High flow to the inlet port 74 of valve 18 :causes the flow sensitive valve 102 to be operated and port tiuidto chamber 58 of the motor to shift the main piston .leftwardly. Upon completion of the motorstroke the directional valve handle 71 returns automatically-, to

the neutral position. To lower the plow rapidly ba'k to the preceding plowing depth position the control h nd le of vvalve 16 is shifted to the L-2 position and temporary high flow from the motor chamber 56 is directed to themotor port 80015 the flow sensitive valve-18 and causes the flow sensitive valve 102 to be operatedpto a position blocking motor chamber 56 from and connecting motor chamber 58 to the port 74 of the valve. 18,

The controlhandle 71 of the valve 16 will returnt the neutral motor stop position after the main piston 36 of the motor comes into abutment with the auxil r piston .38. To adjust the plowing depth the vc ntrol handle 71 of the valve 16 is operated to the L- 1 or'R-1 position and at low flow the-flow sensitive valve member 102 remains in the centered position shown. i Y

Tl1e invention thus provides an eflicient, low-costhydraulic system for remotely controlling the operationof a load device. The length of stroke of the main motor may be adjusted in one direction of operationandthc directional operation of the motor may also be controlled -fr o m for example, a tractor seat, by the operation of only one control lever. This is of importance inplQ ing operations when at the end of a row being plowed the tractor is turned around at which time the plow must be raised and speedily returned to its former plowing depth to start a plowing operation in the OPPOsite direction. The operator of the system need only operate one control lever to the raise and then to the lowering position and when the plow reaches the adjusted pr'eselected plowing depth the motor will stop and the com -fluid ope rated piston therein, the'c'ombination of a hydraulically adjustable stop member for limiting the actuator. Thus, only a single manually operated con- ;trol is utilized for controlling the operation of both the actuator and the stroke limiting member and onlytwo,

dual'function, supply and return conduits are necessary for connecting one station, located on the tractor for example, to the remote station located, forexample, on the trailing implement being towed by the tractor.

While the form of embodiment of the invention "as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1., In a hydraulic power transmission system including a source of pressure fluid and an actuator for drivingga load device of the type comprising a cylinder having a stroke of the piston, a flow sensitive valve hydraulically connected to the stop member and automatically operable in response toone flow rate to cause actuation of the stop member and operable in response toanother flow" rate to lock thestop member in the positionadjusted to, and a manually operable directional control valve hydraulically connected to the pressure fluidsou rc e, ,to the. cylinder and to the flow sensitive valvemetnber for Controlling the directional operation of the piston and the stop member, said control valve having ranges of operation for varying the fluid volume to the cylinder and to the flow sensitive valve.

2. In a hydraulic power transmission system including a source of pressure fluid and an actuator for driving a load device of the type comprising a cylinder having 'a fluid operated piston therein, the combination of a hydraulically adjustable stop member for limiting the stroke of the piston, a flow sensitive valve for porting fluid to and from opposite sides of the stop member dependent on its direction of operation, said valve being responsive to one flow rate to cause actuation of the stop member and being responsive to another flow rate to lock the stop member in the position adjusted to, and a manually operable directional control valve hydraulically interconnected to the pressure fluid source and to the cylinder and the flow sensitive valve, for controlling the operation of the piston and the flow sensitive valve, said control valve having ranges of operation for varying the 'fluid volume to the cylinder and to the flow sensitive valve member.

3. In a hydraulic power transmission system including a source of pressure fluid and an actuator for driving a load device of the type comprising a cylinder having a fluid operated piston therein, the combination of a hydraulically adjustable stop member for limiting the stroke of the piston, a flow sensitive valve responsive to low flow directed thereto to port fluid to the stop member and responsive to high flow thereto to port fluid to the cylinder piston, and a manually operable control valve hydraulically connected to the pressure fluid source and to the cylinder and the flow sensitive valve for controlling the directional operation of the piston and the stop member, said control valve having operating positions for porting low and high flow to the cylinder and to the flow sensitive valve.

4. In a hydraulic power transmission system including a source of pressure fluid and an actuator for driving a load device of the type comprising a cylinder having a fluid operated piston therein, the combination of a hydraulically adjustable stop member for limiting the stroke of the piston, a flow sensitive valve responsive to low flow directed thereto to port fluid to and from the stop member dependent upon the directional operation thereof 7 and responsive to high flow thereto to port fluid to and from opposite sides of the cylinder piston dependent upon the directional operation of the cylinder piston, and a manually operable control valve hydraulically connected to the pressure fluid source to the actuator and to the flow sensitive valve for controlling the directional operation of the piston and the stop member, said control valve having operating positions for porting low and high flow to the actuator and to the flow sensitive valve.

5. In a hydraulic power transmission system including a source of pressure fluid and an actuator for driving a load device of the type comprising a cylinder having a main fluid operated piston therein and an auxiliary stop piston hydraulically adjustable for limiting the stroke of the main piston, the combination of a control valve responsive to one flow rate to port fluid to the stop piston and responsive to another flow rate to port fluid to the main piston, and a manually operable directional control valve hydraulically connected to the pressure fluid source and to the actuator and to the flow sensitive valve,

' said directional control valve having ranges of operation for varying the fluid volume to the actuator and to the flow sensitive valve.

6. In a hydraulic power transmission system including a source of pressure fluid and an actuator for driving a load device of the type comprising a cylinder having a main fluid operated piston therein and an auxiliary stop piston hydraulically adjustable for limiting the stroke of the main piston, the combination of a control valve "responsive to flow of low volume to port fluid to the stop piston and responsive to flow of high volume to port fluid to the main piston, and a manually operable directional control valve hydraulically connected to the pressure fluid source, to the actuator and to the flow sensitive valve, said control valve having operating positions for porting low and high flow to the actuator and to the flow sensitive valve.

7. In a hydraulic power transmission system including a source of pressure fluid and an actuator for driving a load device of the type comprising a cylinder having a main fluid operated piston therein and an auxiliary stop piston hydraulically adjustable for limiting the stroke of the main piston, the combination of a control valve responsive to flow of low volume to port fluid to and from the stop piston dependent upon its direction of operation and responsive to a relatively higher flow volume to port fluid to and from the main piston dependent upon its direction of operation, and a manually operable control valve hydraulically connected to the pressure fluid source, to the actuator and to the flow sensitive valve for controlling the directional operation of the main piston and the stop piston, said control valve having positions of operation for porting low and high flow to the actuator and to the flow sensitive valve. 8. In a hydraulic power transmission system including a source of pressure fluid, the combination of an actuator for driving a load device and including an actuating piston, a hydraulically adjustable stop member for limiting the stroke of the piston, a flow sensitive valve for porting fluid to and from the stop member in response to flow of one volume directed thereto and for locking the stop member in response to flow of another volume directed thereto, and control means for selectively conducting fiow in variable volume to the actuator and to the flow sensitive valve.

9. In a hydraulic power transmission system having two remotely located stations; a fluid operated actuator for driving a load device, a hydraulically adjustable stop member for the actuator, and valve means hydraulically interconnected to the actuator and stop member responsive to one flow rate for effecting operation of the stop member and responsive to another flow rate to hydraulically lock the stop member and effect operation of the motor, located at one station; two fluid conduits leading from the other station to the said one station; and a pressure fluid source and control means for selectively directing a variable flow rate to either of said conduits located at the other of said stations.

10. In a hydraulic power transmission system having two remotely located stations: a fluid motor comprising a cylinder and fluid operated piston, a hydraulically adjustable and lockable stop member for limiting the stroke of the motor piston, and valve means hydraulically interconnected to the cylinder and to the stop member responsive to flow of one rate for effecting operation of the stop member and responsive to flow of another'rate for hydraulically locking the stop member and effecting operation of the motor, all located at one of the stations; two, dual function, supply and return conduits, leading from the other station to the said one station; and a pressure fluid source and control means for selectively directing a variable flow rate to either of said conduits located at the other of said stations.

11. In a hydraulic power transmission system having two remotely located stations, a motor for driving a load device comprising a cylinder with a fluid operated piston therein, said cylinder also having therein a hydraulically operated stop member for limiting the stroke of the motor piston in one direction, and valve means hydraulically connected to the cylinder and responsive at one flow rate to effect operation of the stop member and at another flow rate to hydraulically lock the stop member and eflect operation of the motor piston, all of which are located at one station; two, dual function,

13 supply and return conduits leading from the other station to the said one station, one to the motor and one to the valve; and means forming a pressure fluid source and control means for selectively directing a variable flow rate to either of said conduits located at the other of said stations.

12. In a positional control system having two remotely located stations; a fluid motor and controllable stop means therefor at one of the stations; a variable flow rate fluid source at the other of the stations; conduit means extending between the stations to conduct fluid from the source to the motor; and means at said one station responsive to one flow rate from the source to immobilize the stop and effect operation of the motor and responsive to another flow rate to eflect control of the stop.

13. In a positional control system having two remotely located stations; a fluid motor and controllable stop means therefor at one of the stations; a variable flow rate fluid source at the other of the stations; means at said one station responsive to one flow rate from the source to immobilize the stop and effect operation of the motor and responsive to another flow rate to effect control of the stop; and two, dual function, supply and return conduits extending between the stations connecting the source both to the motor and to the flow responsive means.

References Cited in the file of this patent UNITED STATES PATENTS 2,478,790 Stephens Aug. 9, 1949 2,570,897 Winchester Oct. 9, 1951 2,596,471 Densmore et a1. May 13, 1952 2,604,878 Stevens July 29, 1952 2,614,537 Starr Oct. 21, 1952 2,634,743 Audemar Apr. 14, 1953 FOREIGN PATENTS 999,277 France Oct. 3, 1951 

